I had no clue that IEEE NOMS would have a rebuttal phase. We only submitted to the conference mostly because it was in Japan (if accepted, we'll combine with a trip to the mothership) and the deadline coincided with our post-doc taking a paternity leave, so was not aware of the process of the conference.
I found the rebuttal phase from the reviewer point of view quite useless during the Globecom PC. From the author point of view, the sample is much smaller; it is quite strange that the reviews are provided without the grade, so I'm unable to say if the reviewers liked the paper or not. Obviously they are in between, they don't think it's the best or worst thing ever, but it's hard to decipher if it's leaning one way or the other. I guess it's mostly due to the format of the question, which emphasizes both positive and negative: strength, weakness and detailed (editorial) comments.
I'm not sure how to reply to the reviews, though, not knowing if the job is to not screw it up, or if it's pointless to try to change someone's mind (can a reviewer of an unconvincing paper be turned around in 3,000 characters?)